🔍 Key Concepts

• Dead reckoning (DR) position vs fix on a chart • Effects of wind and sea (leeway) vs current (set and drift) • What factors are and are NOT included when you advance a DR from last known position

💭 Think About

• When you advance a DR position from a known starting point, which forces do you normally include in that plot? Which forces are intentionally ignored? • A fix shows where the vessel actually is. What additional real-world effects can move the vessel off the DR track between times? • Look at each option: which one would change your compass/heading indications, which would push your hull sideways through the water, and which would carry the water (and boat) over the ground?

✅ Before You Answer

• Be clear on the definition: DR position = course and speed through the water only, no external forces • Recall that a fix represents the ship’s actual position over the ground at that time • Identify which choice represents movement of the water itself rather than errors in compass or wind-caused sideways motion of the vessel.